Change-speed conversion unit



April 9, 1947. w. 5. SMITH ETAL 2,419,797

CHANGE-SPEED CONVERSION UNIT Filed April 29, 1944 4 Sheets-Sheet 1INVENTO 5- April 29, .1947.

wp's. SMITH ETAL.

CHANGE-SPEED CONVERSION UNIT 4 Sheets-Sheet 2 Filed April 29, 1944 I...-III.

April 29, 1947. w, s, sM r 2,419,797

CHANGE-SPEED CONVERSION UNIT Filed April 29, 1944 4 Sheets-Sheet 3 I 0 jv v a] 5.

April 29, 1947. w s, SM|TH ETAL 2,419,797

CHANGE-SPEED CONVERSION UNIT Filed April 29, 1944 I N 4 Sheets-Sheet 4Patented Apr. 29, 1947 Wilfred Sydney Smith, Bedford, and Fredrick JamesWalters, Bedford Park, London, England Application April'29, 1944,Serial No. 533,360 In Great Britain June 4, 1942 Ill-Claims. l Thesubject of this invention is a changespeed transmission unit.

Of necessity, certain classes of machine tools and machinery have torun, not at one fixed.

speed, but at alternative speeds according :to the nature of the work onwhich they areengaged.

This change of speed has usually been efiected either by-means of atrain of gears, orby countershaits and standard cone pulleys, limitingthe speed changes to something like three or four 'in number, andnormally making it necessary to stop or-slow down the machinetoeffectthe speed change.

Machines fitted with gear boxes or geared mo- .tors are more compact,but more costly. Machines fitted with cone pulleys are cheaper but needoverhead shafting and countershafting taking up much more :room andusing much more metal.

Machines fitted with gear boxes are easily converted to individualdriving, that -is,'by a motor on the machine'if a change-over isrequired from group driving, thatis, by line shafting, but machinesfitted with cone pulleys have not been easily converted to unit driving.

The chief object of this invention is to provide a change speed.transmission unit suitable for converting cone driven machine tools toindividual drive, or for giving speed changes on single pulley drives,in which the advantages of a geared unit as regards space taken up andease of conversion are obtained at something like half the cost, withoutrecourse to toothed gears :or clutches. A further object is to obtain atotal of not less than seven speeds (or possibly 9 speedsaccording tothe type of unitemployed) on a three-step cone pulley instead of thethree or four speeds normally obtained from gearboxes or other forms oftransmission units, giving twelve speeds if required on a fourstep conepulley, without the necesity of stopping or slowing down the machineWhen a change of speed is required.

According to the invention, an input shaft to receive a constant driveis'assoc'iated with a secondary shaft driven from the said inputshaft-and on one of which shafts are provided change speed pulleysdriven at different speeds to engage a belt, which belt engages a pulleyloosely mounted on the other shaft and which belt remains constantly inone path determined by a pulley on the machine that is to be driven,lateral movement of the complete unit, by displacing the shafts andpulleys thereon relatively to the *belt,

causing the belt to assume the speed of the pun I 2 ley which at thetime is passed under it, and thereby to effect changes in the speed to"be transmitted to the machine. The-constant drive may be obtainedeither from a motor on the unit, or if required by a direct drive fromline shafting to the input shaft, when the advantages of a geared headmachine would'be obtained with additional speed changes-whilst running..The power transmitted by'the motor does not fall with :a reduction inspeed. The :transmission unit can be combined with ordinary ormodifiedcone driving gear, whereby agreatly increased range of speeds isobtained, with .the advantage of being able to obtain speed :changeswhilst the machine is running.

For certain classes of machinerya quick "reverse in direction ofrotation is necessary. Reversal can easily'be obtainedelectrically-but'electrio reverse has the disadvantage that speciallywound motors are necessary if frequent reversals are required. Also themotor and machine'must be allowed to come to rest in one direction :ofrotation before being switched over to the ;opp.o site direction. It istherefore obvious that if :a reversal in the machine could be obtainedwhilst the motor continued to run in the same direction of rotation,several advantages would :be gained including a saving of time in any.particular operation. It is therefore proposed that where thusrequired, the reversal should be .obtained in the unit and notelectrically.

In order that the said invention may be clearly understood and readilycarried into effect, the same will now be more fully described withreference to the accompanying drawings.

Figure 1 represents in end elevation a device for embodying one form ofthe invention.

Figure 2 represents the same device in front elevation.

Figure 3 is an end elevation of a modified form.

Figure .4 is a front elevation of the device shown in Figure .3.

Figures 5 to 11 represent details hereinafter described.

Figure 12 is a diagram illustrating the path of the belt I! in Figure 3.

Figures '13, 14 and 15 illustrate a'modification in which a reversal .ofthe drive can be obtained in the unit and not electrically, Figure 13representing a front elevation of the unit with the guards removed toreveal the driving arrangements, and Figures 14 and 15 arediagramsillustrating the method of obtaining reversal in this 3modification, in which different reference numerals are used for thesake of clearness.

As will be shown the units detailed in Figures 1, 2, 3 and 4 arebasically the same and differ only in their method of operation. In bothtypes the principle employed is identical and for equivalent unitsthe.driving components are interchangeable.

Referring first to Figures 1 and 2, G indicates a bracket or frame onwhich the whole of the conversion unit is mounted, this bracket beingmovable in either direction along a base plate Y. A indicates a standardhigh speed electric motor, mounted with its starter B on an adjustableplate C hinged at C. From a V grooved pulley 2| on the shaft of themotor, V ropes l2 drive a similarly grooved pulley I3 on a shaft E,which may be termed the main shaft or in this case the input shaft ofthe unit, the ratio of this drive depending on the ultimate speedsrequired. In the case of a three-step cone machine the speed of theinput shaft would normally be the middle speed required on the machine.The input shaft E is carried by two ball bearing plummer blocks F, F,which are in turn carried in slots P in the main bracket G. The baseplate C of the motor A is hinged at C to the bracket G, and isadjustable by means of a nut which when the motor is tilted backward,can be inserted in the part of the bolt C between the plate C and theframe G. The plate C is slotted for the free passage of the bolt C andthe bracket G is threaded to engage the said bolt; when the bolt isscrewed back to release the plate C the motor can be tilted backward anda nut C can be inserted on that portion of the bolt which is to bebetween the bracket G and plate C, thereby holding the plate C securebetween the bolt head and the nut C this arrangement being duplicated onthe other side of the unit. The nut C when not required can be placed onthe free end of the bolt C as shown in Figure 1, so that it will behandy for use when it is required. In the position shown, in which theplate C is held closely against the frame, the nut is unnecessary, asthe plate is prevented from moving by the bolt C Adjustment of the .belttension of the initial drive from the motor A to the input shaft E isthus obtained.

'On the input shaft E are two fast pulleys H and K, Figure 2. The pulleyH is suitable for the use of a fiat belt, and the pulley K is V groovedto receive V ropes S for driving a counter-shaft or secondary shaft L.This shaft L is carried by two ball bearing plummer blocks P, P, securedon the bracket G, and on the said shaft L are three fast transmissionpulleys M, N and O. M is driven by flexible transmission elements, ropesS, while the two latter pulleys are V grooved and drive back by ropes Son to the driven pulleys Q and R, which are loose on the shaft E, eachof these pulleys Q and B being made integrally with a fiat or crownfaced change speed pulley Q, R of the same diameter and face width asthe change speed pulleys H. The ratio of the drives NQ and OR are in thesame proportion, but one is a step-up and the other a step-down drive.Consequently the fiat belt pulleys Q, H and R, running side by side,revolve at three different rates of speed. Due to the fact that theshaft E, on which these pulleys rotate, is revolving in the samedirection as the loose pulleys QQ' and RR, the speed of these pulleysrelatively to the shaft is not great, and gun-metal bushed pulleys, orball bearing pulleys,

4 with provisions for lubrication, are adequate for the job. The widthof the fiat belt pulley H, and of the flat belt pulley portions Q and R,is either the same as the face width of the machine cone pulleys or issufficient to transmit whatever power is required.

The lay-out is made as compact as possible, this minimizing the lengthof the V ropes S operatively connecting the shafts E and L and reducingthe possibilities of their stretching. The said ropes are all of thesame section and length, are all doing the same amount of work, and areall in motion at the same time, consequently any stretch that occurs isuniform, and it can be taken up by raising the plummer blocks P in theslots P in the bracket G, as shown in Figures 1, 2, 3 and 4 an eye-bolt4| can be attached to the top plummer blocks, which eye-bolt passesthrough a lug on the bracket G, when adjustment can be obtained bytightening a nut on the eye-bolt, on top of the lug, thus drawing theplummer blocks P and. shaft L away from the shaft E.

Between the pulleys N and O on the shaft L is a loose jockey pulley T,running on ball bearings above which is another loose jockey pulley U(also running on ball bearings) on a shaft V carried in adjustablesaddles W which are supported on the bracket G, by means of threadedstuds X which are secured in the bracket G but are free to rotate withinsame. The shaft V is adjustable, in that it can be raised or lowered bymeans of the threaded studs X the rotation of which studs causes thesaddles W to be raised or lowered on their threads. The saddles arethreaded to take the studs, so that rotation of the studs causes thesaddles to rise or fall. Alternatively, spring adjustment may beemployed as shown in Figures 5 and 6 where the supporting saddles W arefitted in studs 3| which are secured to the bracket G. Around the topportions of these studs, springs X are located by a lug 23 in thebracket G and by the saddles W themselves, and a fiat belt I! is fittedwith the springs compressed, the springs thus automatically taking upany slack in the belt due either to belt stretch or to moving the beltfrom step to step of the machine cone pulley, the point being that shaftV is adjustable.

The bracket G, which carries the whole of the equipment, including themotor and its starter, is movable backwards and forwards on a base plateY, by means of a square threaded lea-d screw I4, which passes throughthe base plate and is located by the operating hand-wheel Z at one endand a collar Y at the other end. In the base of the bracket G are twothreaded nuts or lugs to mesh with the square threaded lead screw, thearrangement being such that when the operating hand-wheel Z is turned,the bracket G with its equipment travels backwards or forwards along thebase plate Y and can be left in any position along the said base plate.

A flat belt I! (see Figures 3 and 12) is passed around the drivingpulley H to the back of the jockey pulleys T and U and runs across atshort centres to the middle step of the machine tool step cone pulleyHi. When the motor is connected and started, the speed at which themachine rotates can be adjusted by the operating hand-wheel Z, whichdraws one of the driving pulleys Q, H or R, with their different speedsunder the flat driving belt I! which then assumes the speed of thepulley over which it is running and drives the machine accordingly,

should additional speeds be required, the hat belt II can be movedfrom-the centrestepof the machine cone :pulley l8 as in Figure 3 and runon to either of the other steps, th flat belt driving tension beingmaintained by the top ijockey pulley U, on the adjustable shaft *V. Thuswith the existing three step cone pulley on the machin tool, a maximumof three Speeds can be obtained in each step, according to whether Q, Hor R (with their different driving speeds) is the driving pulley.Consequently, a total of'nine "speeds is possible.

The conversion unit issmall vandcompact and can be bolted direct on tothe machine, thus making it individually or unit driven, and becoming.partcf the machine. It can be secured at any angle as the bracket G-not only slides on the machined seats of the base plate Y, but on shaftsCi by which the bracket is attached to the base plate. The shafts G arefixed in the base plate Y and the bracket G is slidable on them. Thus,if necessary, the unit could be .inverted as the bracket G would besecurelyiheld :hy shafts G on which it would then travel when theoperating hand-wheel Z was actuated.

Referring now to Figures 3 and 4, instead of shafts G bein fixed in abase plate, and the bracket G sliding on these shafts, the said shaftsare fixed in the bracket G, and are themselves slidable in thesupporting bracket Y, which takes the place of the base plate Y in theexample illustrated in Figures 1 and 2. For changingspeeds, movement ofthe bracket G is effected by turning the three-armed capstan type handlever Z" at the top of the unit, which causes an upright operating shaft4 to rotate. A pinion ion theshaft 4 meshes with arack 6 (Figure 4)which connects the two upright portionscf the bracket this rack and thebracket G being preferably cast in one piece. The pitch diameter ofthe-pinion is .such that when one .of the knobs of :the three-armedlever .Z' is moved to the front, it brings one of-the driving-pulIeys Q,H or R underneath the flat belt l-I driving the machine to obtain aselected speed. The shaft :4, on which-the pinion is mounted is locatedin .ahole drilled for this'purpose in the supporting bracket Y and ismade rigid by a supporting-saddle 8, which is also bolted to the bracketY. The collar 1 prevents the pinion being lifted out of mesh with-therack.

In this modification it is found convenient to make the top jockeypulley U and shaft V adjustable .by springs. As shown in Figure .3, thesupporting saddles W are fixedto shafts 32 which are sunk into thebracket G. Around the tree portion (that .is, the part not secured insaddle W and therefore free to move up and down in the bracket G) oreach shaft 32 springs X are located byzsaddles W at the :top and by ashoulder 33 in casting G at the bottom so that if the flat :belt H isfitted whilethespringsare compressed, the springs automatically take upany slack in the belt'dueto stretch ortomoving the belt from steptester-of the cone pull y- Themotor A is fitted on slide rails 0,instead of on a hin ed plate 'C as in Figures 1 and 2. By means of anadjusting bolt 25, the slide rails can be moved up or .down the machinedand slotted back :ofthe bracket G. Slots in the rails also provide forlateral movement, so that it is possible to move the motor eithervertically or horizontally; thus the fitting of any motoris simple, andthe :ne- .cessity of drilling holding-down bolt-holes is avoided. Theinput shaft drive from :the motoris 6 taken directlyatovthelupper;shaftL, and this :can

also be donein-the case-of theexamplezshownin Figures .1 and. 2 when sorequired. An extension 9 on :thebottom shaft can beused for taking anauxiliary, drive, .for example to a machine tool suds pump. Theextension could alternatively be on the inputshaft. It will be notedthat any drivetakencff theextensionQ will be at a constant speed,although the unit and machine speeds maybechanged by the capstantypecontrol lever or hand wheel. A metalguard 21 is fitted across the frontof'th'e unit, .both as a safety precaution and-to prevent suds pumpsplash or swarf'being carried into the unit. .sAnother metal guard 28(shown open in Figure 4 to expose "the grooved pulleys ,to-view)completely encases the connecting driv MK.

It will be evident that the units hereinbefore described in Figures .1and;2'and in Figures3 and respectively are basically the same, that.is,the mechanisms vare identical .in principle, and for equivalentunits, thedriving components are interchangeable, but for certainapplications one method of operation-either hand-wheel control or threepoint capstan control lever-may .be more advantageous than the :other.

With the unitshown in Figures 1 and 2, the extent of movement of thebracket is sufiicient to allowof three speeds being obtainedon each stepof the cone pnlley,;but with the unit shown in. Figures 3 and 4, itmay'in some cases be inconvenient to permit the amount of traversenecessary to give the three speedson the largest and-smallest stepsof'the driven cone Pulley, and the unit can be arranged to give threespeeds onzthe middle step, and twoeach on the largest and smalleststeps, while reducing the width of the bracket by twice the .width ofeach step of the cone pulley. The two shafts may be parallel verticallyas shown or in any other plane.

It is not intended that the conversion unit should be used solely forconverting group driven machines :to individual drive. It can be builtinto new installations, opposite either a single diameter .or step conepulley ,of the type described hereinafter when speed changes arerequired.

Many machine tools are still manufactured with cone pulley drives, dueto the expense of the alternative forms of change speed drivessuchastoothedgears.

Inv suchnew installations it is proposed that the cone pulley on"the'machine tool should be made as "shown in Figures 7 and 8, with aninclined rise ,29:steppingaup one diameter to the other instead of eachdiameter rising vertically to the next. The adjustable top shaft V ofthe conversion unit, carried insaddles W as already referred to, will insuch cases'be spring controlled as described with reference to Figures3, 44, 5 and 6.

To enable the advantage of quick speed changes itO be obtained onexisting machines, which might be ,fltl'led with the standard type ofstep cone'pulley in which the diameter falls vertically from one step tothe next, it is proposed to supply separate inclined wedge shaped risingsections 38 as shown in Figures 9, 10 and 11. These 'will be made in avariety of sizes, to suit the varying drops in diameter likely to beencountered. Two or more of these must be fitted to each step by meansof a set screw, against the wall separating one diame er of the conefrom the other, thereby supplying the flat belt withtheslead-itrequires.

When these risers are applied .to ex sting machines, the narrower fiatbelt might not be capable of transmitting the necessary power, so thatif necessary to compensate for the loss in belt width due to the fittingof the rise, a thicker belt can -be employed to transmit the powerrequired.

The travel of carriage or bracket G will be so arranged that at theconclusion of the complete speed range on any one step of the machinecone pulley the flange dividing the grooved pulley and fiat faceportions of pulleys Q and R will push the fiat belt from that step on tothe next diameter step. When the belt is pushed from a larger to asmaller diameter step, the tension in the springs will be such that theyimmediately adjust the top shaft V so that the correct driving tensionis maintained on the belt.

Similarly, when the belt is pushed from a smaller to a larger diameteras it engages the inclined rise on the machine cone pulley, the tensionin the fiat belt will be increased, thus compressing the spring X,causing a reduction in the height of the top shaft V, and allowing thebelt to pass on to the next diameter of the machine cone pulley.

In this way, not only would three speeds be obtained on each step of themachine cone whilst running, without the necessity of stopping orslowing down, but the full range of the unit could be obtained on theother two steps without having to stop or slow down to adjust the beltfrom one step to the other on the machine cone.

The jockey pulleys on the unit are so arranged that the fiat belt H hasan arc of contact, or gripping surface on the pulley H of something like250 degrees, as compared with an average drive of about 140 degrees laparound the smaller pulley, so that a very good drive is provided.

It should also be noted that where necessary or expedient due to theconditions under which the unit may be called upon to work, the drivesNQ, OR or MK can be effected by means of chains, or toothed gears atfixed centres, instead of by V ropes. The principle of operation andlayout otherwise remain exactly as described.

It will be seen that the change speed unit herein described is a compactmeans of converting group driven plant to individual drive, and/or ofobtaining speed changes in the drive on to any form of pulley, whetherof cone or single diaameter. It permits three speed changes to beobtained whilst running on any single pulley diameter, and when used inconjunction with three-step existing cone pulleys allows a total of ninespeeds to be obtained without the use of clutches. The use of inclinesbetween the steps of the cone pulleys renders it unnecessary to stop orslow down the machine when making any change, and the operator can passrapidly, without pause, to any speed in the range that he may require.It is important that such drives as suds pump drives should run atconstant speed although the main drive varies, and this can be effectedby the method described. Any standard motor can be easily fitted to theunit without the necessity of drilling holes at varying centres due tothe slots in the side rails and the possibility of vertical adjustment.In using the capstan three point control lever, positive indications ofspeed are obtained by observing which of the three knobs is at thefront.

The method of obtaining a reversal of the drive is illustrated inFigures 13 to 15. Here, as previously described, either shaft may betaken as the input shaft. In Figure 13 the unit is driven 8 through theinput shaft pulley which causes the top shaft to rotate at any desiredspeed. On this shaft three other fast pulleys are secured, namely,transmission pulleys 5|, 53 and change speed pulley 51.

From the pulley 5| the drive is taken at any required ratio to thecombined pulley 52 which runs loose on the secondary shaft, and which iscombined'with a fiat belt pulley portion as previously described.

From the transmission pulley 53 a similar drive is taken to the pulley54, which is fast on the secondary shaft and causes this shaft to rotateat any desired speed according to the ratio of the drive.

Usually drives 5| to 52 and 53 to 54 have the same ratio, one being aspeed-up, the other a step-down.

The fiat face pulley 55 is also secured to the secondary shaft so thatit rotates at the same speed as the pulley 54, thus pulleys 52 and 55rotate side by side at different speeds of revolutions per minute.

A loose pulley 58 of th same diameter and width as the fiat face portionof pulley 52 and pulley 55 is located between pulleys 55 and 54 and thusruns opposite the fixed pulley 51 which has the same diameter and widthon the top shaft (input shaft).

A loose pulley 56 carried on to the top shaft is located between fastpulleys 5| and 51 and runs opposite the flat faced portion of pulley 52,and pulley 55 is equal in diameter to them and its width is equal totheir combined width.

The method of operating the unit is exactly the same as hereinbeforedescribed according to the type of unit, and the flat belt connectingthe unit to the machine is arranged as previously detailed, and as shownin diagrams Figures 14 and 15 which represent the arrangement in sideview.

When the unit is operated the flat belt is driven either by pulley 52,or 55 in one direction of rotation at their different speeds, but whenon operation the unit moves across for the belt to engage pulleys 58 and51, the driving function is transferred from the bottom to the top shaftand is obtained from the pulley 51, with the result that although pulley51 is rotating in the same direction as the other driving pulleys 52and55, the direction of rotation of the belt is reversed as will be madeclear by reference to Figures 14 and 15, Figure 14 representing thedrive when taken from either of the bottom driving pulleys 52 or 55,Figure 14 representing the drive when taken from pulley 51. It will beobserved that as the driving function is transferred from pulley 5-5 to51, or vice versa, the resulting action of the pulleys is first to slowdown, then to brake, and then reverse the direction of rotation of thebelt, because as the pulleys move under the belt, they are tending topull it in opposite directions.

The top shaft is indicated at 60, and the cone or other pulley on thedriven machine at 6|.

Thus the reverse is immediate as the unit applies its own brake. Themotor and the extension shaft 59 which drives the auxiliary (such assuds pump) continue to rotate in the same direction throughout. Thus twospeeds forward and one in reverse are possible on any single diameterstep of the machine pulley.

In the same manner if it was required it would be possible to introducea third drive on the right-hand side of the bracket (outside thebracket) to give a total of three speeds forward and one reverse.

What we claim and desire to secure by Letters Patent of the UnitedStates is:

1. In a change speed unit, an input shaft adapted to receive a constantdrive, and associated therewith a secondary shaft adapted to be drivenat constant speed from said input shaft; transmission members associatedwith said shafts, driving change speed pulleys adapted to be driven atdifferent speeds by means of said shafts and transmission members andarranged upon said input shaft; a belt, a driven pulley loosely mountedon said secondary shaft; said belt adapted to be engaged alternativelyby each one of said driving change speed pulleys on said input shaft andto engage said driven pulley loosely mounted on said secondary shaft; anoutput pulley arranged to be driven by said belt and for driving amachine; means for displacing said change speed unit laterally andrelatively to said belt, so as to cause said belt to assume the speed ofthat of said driving change speed pulleys which at the time is passedunder it, thereby to effect changes in the speed of said output pullayand the machine driven thereby.

2. A change speed unit as set forth in claim 1 including a motorarranged for deriving therefrom the constant drive of said input shaft.

3. A change speed unit as set forth in claim 1 including a motorarranged for deriving therefrom the constant drive of said input shaft,a base plate for said motor, a frame carrying said change speed unit,said base plate hinged to said frame.

4. A change speed unit as set forth in claim 1 including a motorarranged for deriving therefrom the constant drive of said input shaft,a frame carrying said change speed unit, and slide rails on said frame,said slide rails adapted to mount thereon said motor adiustably forfourway movement.

5. A change speed unit as set forth in claim 1 wherein a base plate infixed spatial relationship to said driven machine is provided and saidunit is slidably arranged on said base plate and relatively to saidbelt; said transmission members including fast pulleys on said secondaryshaft and loose pulleys on said input shaft and flexible transmissionelements for engaging said fast and loose pulleys, said fast pulleysarranged to drive back, by means of said flexible transmission elementsonto said loose pulleys and to impart to them speeds at variance withthe speed of said input shaft and for thus to impart various speeds tosaid change speed pulleys and through said belt to said output pulleyand said machine driven thereby according to the position of the unitrelatively to said fixed base plate and said belt.

6. In a change speed unit, an input shaft adapted to receive a constantdrive and associated therewith a secondary shaft adapted to be driven atconstant speed from said input shaft; change speed pulleys comprisingdriving and driven pul- 10 leys arranged oppositely of one another onsaid shafts, transmission pulleys arranged in opposite pairs on saidshafts and including driving transmission pulleys fast on said inputshaft and driven transmission pulleys loose on said secondary shaft,flexible transmission elements connecting said driving and driventransmission pulleys whereby speeds at variance with the speed of theinput shaft are imparted to said transmission pulleys; said change speeddriving pulleys arranged for being driven at different speeds by meansof said shafts and said transmission pulleys; a belt associated withsaid change speed pulleys, an output pulley adapted to be driven by aidbelt and to drive a machine; a base plate disposed in fixed spatialrelation to said machine, said unit mounted slidably on said base plateand relatively to said belt for causing, on displacement of said unit,the belt to assume the speed of that of said driving change speedpulleys which by such displacement is at the time passed under it,thereby to effect changes in the speed of said output pulley and saidmachine driven thereby.

'7. A change speed unit as set forth in claim 1 wherein said outputpulley is a cone driving gear whereby to obtain a greatly increasedrange of speeds for said machine.

8. A change speed unit as set forth in claim 1 wherein said outputpulley is a step cone and inclined risers are provided at the lateralfaces of said steps for joining each step of said cone to next, saidrisers consisting of wedge shaped sections secured to said faces.

9. A change speed unit as set forth in claim 1 wherein means areprovided on at least one of said input and secondary shafts for taking aconstant drive from said shaft to an auxiliary mechanism.

10. A change speed unit as set forth in claim 1, said change speedpulleys including fast and loose pulleys in opposite pairs on each ofsaid input and secondary shafts, means for displacing said unitrelatively to said belt, said unit, by various displacements withrelation to said belt, adapted to engage said belt with a fast pulley onsaid secondary shaft to transmit to said belt a drive in one direction,and to engage said belt with a fast pulley on said input shaft toreverse the direction of said drive.

WILFRED SYDNEY SMITH. FREDRICK JAM'ES WALTERS.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,029,053 Brennen Jan. 28, 193635,729 Butler et a1 June 24, 1862 955,920 Stevens Apr. 26, 1910

